Method for operating a component part disposed in an exhaust gas region of an internal combustion engine and device for implementing the method

ABSTRACT

A method for operating a component part situated in an exhaust gas region of an internal combustion engine, and a device for carrying out the method are proposed, in which, in a first operating phase, an exhaust gas component is embedded, and which, in a second operating phase, is regenerated from the exhaust gas component. The second operating phase may be started both as a function of the operating state of the component part and/or as a function of the operating state of the internal combustion engine, and also by an external start signal. If there is an external start signal present, the second operating phase is preferably only started if, at the same time, at least one additional conditions is satisfied. The external start signal is made available, for instance, by a diagnostic unit which is connected via a diagnosis interface.

FIELD OF THE INVENTION

The present invention relates to a method for operating a component partdisposed in an exhaust gas region of an internal combustion engine and adevice for implementing the method.

BACKGROUND INFORMATION

German Published Patent Application No. 199 06 287 describes a methodfor regenerating a particulate filter disposed in the exhaust gas regionof an internal combustion engine, in which changes are made betweenvarious operating states as a function of the most recently presentoperating state, and as a function of the state of the particulatefilter. In one operating state, a regeneration of the particulate filterfrom the embedded particles takes place.

The regeneration takes place at an increased temperature, at which theparticles, chiefly soot particles and ash particles, are burned by anoxidation reaction. In the average operation of an internal combustionengine, the temperature of the particulate filter lies in a temperaturerange of 150 to 300 degrees Centigrade, in general, therefore, below thetemperature required for the regeneration. Therefore, in general,special heating measures are required in order to initiate regeneration.The required temperature may be reached, for instance, via an increaseof the temperature of the exhaust gas of the internal combustion engine.Since the exhaust gas has to heat up, besides the particulate filter,additional component parts that may be present, that is, the exhaust gasregion as a whole, some minutes may pass until the regeneration starts.An estimate of the duration of the regeneration, that is a function ofthe loading state of the particulate filter and of its size, wouldcurrently be up to 25 minutes.

If the internal combustion engine is situated in a motor vehicle,situations are conceivable in which a complete regeneration of theparticulate filter is not possible or is not even able to be begun. Suchsituations, on the one hand, are fault states such as an engine oildilution by a previous regeneration. On the other hand there may beoperating states present in which the internal combustion engine doesnot even reach its own nominal operating temperature. Such an operatingstate occurs, for example, in short-range operation of the motorvehicle. In this case, a regeneration procedure may perhaps be brokenoff or may not start in the first place.

German Published Patent Application No. 198 43 879 describes a methodfor operating an internal combustion engine, in whose exhaust gas regionan NOx adsorption catalyst is situated. In a first operating phase inwhich the internal combustion engine is driven using a lean mixturewithin the scope of a stratified cylinder charge, the NOx created isstored in the NOx adsorption catalyst. In a second operating phase, inwhich the internal combustion engine is operated with a stoichiometricor rich mixture within the scope of a homogeneous cylinder charge, theNOx adsorption catalyst is regenerated. As in the particulate filter,the regeneration of the NOx adsorption catalyst takes place at increasedcatalyst temperatures, compared to normal operating conditions, whichare able to be reached using special catalyst heating measures. Theduration of the regeneration of the NOx adsorption catalyst lies withinthe range of seconds, and is therefore considerably shorter compared tothe duration of the regeneration of a particulate filter. Still, basedon the required heating measures, in principle, the same problems occuras in the regeneration of the particulate filter. Here, too, situationsare conceivable in which the regeneration is broken off or is notstarted in the first place.

SUMMARY OF THE INVENTION

The object of the present invention is to specify a method for operatinga component part disposed in an exhaust gas region of an internalcombustion engine and a device for implementing the method which ensurethe operating readiness of the component part. The method according tothe present invention and the device according to the present inventionfor carrying out the method provide that, in a first operating phase, anexhaust gas component of the internal combustion engine is embedded in acomponent part situated in the exhaust gas region of the internalcombustion engine, and, in a second operating phase, the component partis regenerated from the embedded exhaust gas component. The secondoperating phase is started as a function of the operating state of thecomponent part and/or as a function of the operating state of theinternal combustion engine. According to the present invention, it isprovided that the second operating phase is furthermore started by anexternal start signal.

The measure according to the present invention makes it possible toensure the operating readiness of the component part in that theoperating phase, in which the component part is regenerated from theembedded exhaust gas component, is able to be started at will, using theexternal start signal. The regenerated state of the component part maybe produced, for example, by an operator, as desired. The desire to dothis may occur during service performed on the internal combustionengine and the components assigned to it. If the internal combustionengine is situated in a motor vehicle, the demand may occur within thescope of stays in a repair shop. The measure according to the presentinvention makes it possible to put the component part into a specifiedstate that is equivalent to the regenerated state. In this application,the measure according to the present invention makes possible thediagnosis of the internal combustion engine and the components assignedto it, starting from the regenerated state of the component part. Thevehicle operation of the motor vehicle, that was possibly restrictedbefore, may be restored again.

A first further refinement provides that the external start signal isguided via a diagnosis interface. These days, diagnosis interfaces areusually present, provided the internal combustion engine is situated ina motor vehicle. In this application, normalized interfaces will infuture be prescribed by law, so that one may assume their increasingavailability. The external start signal is preferably made available bya diagnostic unit which may be contacted in a simple manner if adiagnosis interface is present.

Another refinement provides that, when the external start signal ispresent, the second operating phase is started only if at least oneadditional condition has been satisfied at the same time.

Such a condition is, for instance, that the temperature and/or therotary speed of the internal combustion engine lie within a prespecifiedrange. A further condition is, for example, that the speed of a motorvehicle is equal to zero. Still another condition is, for example, thata performance specification signal of the internal combustion enginecorresponds to an idling value, at which the internal combustion engineis at least within the range of its idling speed. Yet another conditionis, for instance, that an idling controller, that is included in thecontrol system of the internal combustion engine, is in a steady state,at which the idling speed regulation of the internal combustion engineis held at least approximately constant.

One embodiment of the method according to the present invention, and ofthe device according to the present invention for carrying out themethod, provides that, in the second operating phase of the internalcombustion engine, an increase in the temperature of the exhaust gas ofthe internal combustion engine is provided.

The method according to the present invention and the device accordingto the present invention for carrying out the method are particularlysuitable for producing the operating readiness of a catalytic converterdesigned as catalytic converter with hydrogen trap, especially as an NOxadsorption catalyst and/or a particulate filter, preferably a Dieselparticulate filter.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE shows a technical environment in which a method according tothe present invention proceeds.

DETAILED DESCRIPTION

The FIGURE shows an internal combustion engine 10 in whose intake areaan air mass flow sensor 11 is situated, and in whose exhaust gas region12 a temperature sensor 13 and a component part 14 are situated. Airmass flow sensor 11 emits an air mass flow signal msl to a controlsystem 15. Temperature sensor 13 makes available to control system 15 atemperature tabg of the exhaust gas of internal combustion engine 10.Control system 15 also has supplied to it a performance setpoint signalps, a rotary speed signal n of internal combustion engine 10, as well asa regeneration signal r made available by a regeneration control system16 Control system 15 emits a fuel metering signal msk to internalcombustion engine 10, emits an exhaust gas recirculation signal agr toan exhaust gas recirculation valve 17 which sets a recirculated exhaustgas quantity 18, and emits an idling controller signal lr to a conditiontester 19.

Rotary speed signal n and performance setpoint signal ps are also madeavailable to condition tester 19. Condition tester 19 also receives aspeed signal v, an engine temperature signal tmot and an external startsignal s that are supplied to it. External start signal s is madeavailable by a diagnostic unit 20, and is passed on to condition tester19 via a diagnosis interface 21.

Condition tester 19 emits a regeneration release signal rf toregeneration control system 16. Furthermore, a pressure differencesignal dp is supplied to regeneration control system 16, which makesavailable a pressure difference 22, which records the pressuredifference of the exhaust gas in front of and behind component part 14.

The method according to the present invention and the device accordingto the present invention for carrying out the method operate as follows:

As a function of performance setpoint signal ps, control system 15 setthe fuel quantity, that is to be supplied to internal combustion engine10, using fuel quantity signal msk, which is supplied to a system thatmeters in fuel and is not shown in detail. In this instance, air massflow signal msl is taken into consideration, which is made available byair mass flow sensor 11, which is situated in the intake region ofinternal combustion engine 10. If internal combustion engine 10 is aDiesel internal combustion engine, in principle, no additional inputvariables are needed for setting fuel quantity signal msk. If necessary,an exhaust gas sensor is provided, that is not shown, which emits alambda signal to control system 15, as a measure for the air-fuel ratioin the exhaust gas of the internal combustion engine. Also not shown isa possibly present throttle valve in the intake region of internalcombustion engine 10, which either emits a throttle valve signal tocontrol system 15, or which is activated by control system 15.

The concentration of nitrogen oxides in the exhaust gas of internalcombustion engine 10, as well as temperature tabg of the exhaust gas maybe influenced using recirculated exhaust gas quantity 18, which controlscontrol system 15 via exhaust gas recirculating valve 17 using exhaustgas recirculating signal agr.

Component part 14 may be, for example, an adsorption catalyst whichembeds a prespecified exhaust gas component in a first operating phase.In the related art named at the outset, the adsorption catalyst isembodied as an NOx adsorption catalyst which stores the nitrogen oxidescontained in the exhaust gas in the first operating phase of internalcombustion engine 10. Since the storage capacity of such an adsorptioncatalyst is limited, the adsorption catalyst occasionally has to beregenerated in a second operating phase. The necessity for thisgeneration may be determined in regeneration control system 16, forinstance, in the light of NOx mass stored in the adsorption catalyst,the NOx mass appearing behind the adsorption catalyst, the NOx mass flowappearing in front of and behind the adsorption catalyst, or in thelight of other criteria. The appearance of regeneration signal r showsthe regeneration required for component part 14. A change from the firstto the second operating phase may then be directly brought about.Control system 15 may, however, prevent the change required per se, inthe light of determined operating conditions of internal combustionengine 10.

In the exemplary embodiment shown, component part 14 is a particulatefilter, especially a Diesel particulate filter, which embeds the sootparticles contained in the exhaust gas of internal combustion engine 10,in the first operating phase. Regeneration control system 16 mayascertain the loading state of the particulate filter, for instance, inthe light of the pressure difference occurring in the exhaust gas infront of and behind the particulate filter. The pressure difference ismeasured by pressure difference sensor 22, and is made available aspressure difference signal dp. If the loading limit of the particulatefilter exceeds a predefined measure, then regeneration control system 16emits regeneration signal r to control system 15. In this exemplaryembodiment too, a change from the first to the second operating phasemay then be directly brought about. Here, too, control system 15 may,however, prevent the change required per se, in the light of determinedoperating conditions of internal combustion engine 10.

Such operating conditions are, for example, an operation of internalcombustion engine 10 during the warm-up phase, temperature tmot ofinternal combustion engine 10 being able to be measured, for instance,by a temperature sensor, that is not shown, that is situated, forexample, in the cooling water, on the cylinder block or in the oilcirculation. A change to the second operating phase is furtherprevented, for example, if internal combustion engine 10 is in idlingoperation. In this operating state, temperature tabg of the exhaust gasis so low that the fuel requirement for heating up component part 14would be too large. A change to the second operating phase is furtherprevented, for instance, if the distance in time to a prior secondoperating phase is too short. In this context, it should be taken intoconsideration that an oil dilution during the second operating phase mayoccur by a heating method in which a postinjection of fuel is provided,which partially condenses on the cylinder walls of internal combustionengine 10, and gets into the engine oil. If these operating situationsare present, the second operating phase is just not started in the firstplace. Furthermore, one has to take into account that the secondoperating phase cannot be shut down. This case arises if internalcombustion engine 10 is switched off during the presence of the secondoperating phase.

According to the present invention, it is provided that the secondoperating phase is able to be started, independently of the operatingstates of internal combustion engine 10 and/or the state of componentpart 14, using external start signal s. External start signal s may, forexample, caused by a service technician within the scope of maintenance.External start signal s makes it possible to be able to shift componentpart 14 into the regenerated state at any time. The further diagnosismay then proceed from a specified initial state.

External start signal s could, for instance, take place by a simpleshort-circuiting of a contact which, for example, is connected tocontrol system 15. A simple handling occurs if start signal s isconveyed via disgnosis interface 21. Such a diagnosis interface 21 ismostly already available these days. In the future, the availability ofdiagnosis interface 21 will be increased because of legal regulations.Start signal s is preferably made available by diagnostic unit 20, whichis contacted to diagnosis interface 21. Diagnosis interface 21 may beimplemented both as a mechanical plug connection and as a radiocommunication.

In one simple embodiment, external start signal s may directly cause thestart of the second operating phase, in which component part 14 isregenerated. Preferably, however, condition tester 19 is provided, whichadditionally tests, when an external start signal is present, whetherprespecified conditions are present, and which, using regenerationrelease signal fr, releases the second operating phase only when atleast one condition is satisfied.

A first condition determines that temperature tmot of internalcombustion engine 10 has to exceed a threshold value. Another conditionprovides that the driving speed of a motor vehicle, in which internalcombustion engine 10 is situated, is equal to zero. Using this measure,it is checked whether external start signal s was actually caused duringa service stay. Furthermore, it may be tested whether rotary speed n ofinternal combustion engine 10 is in the range of the idling speed.Particularly advantageous is checking whether performance setpointsignal ps corresponds to a value at which internal combustion engine 10is operated when idling. Performance setpoint signal ps is madeavailable, for example, by an accelerator situated in the motor vehicle.Using this measure, it is additionally ensured, if necessary, thatinternal combustion engine 10 is being operated at a rotary speed n inthe idling speed range. Using idling control signal lr, one may thenadditionally ensure that internal combustion engine 10 is being operatedat a rotary speed n in the idling speed range, and that no request forchanging the rotary speed is present or that no increased idling speedis present, as, for example, might be specified during warmup of theinternal combustion engine. Consequently, condition tester 19 forms anAND link of external control signal s with the presence of at least oneof conditions tmot, v, n, ps, lr. Only if the at least one conditiontmot, v, n, ps, Ir is satisfied, condition tester 19 releasesregeneration release signal Fr to regeneration control system 16.Regeneration release signal Fr has preference compared to pressuredifference signal dp, which indicates the loading state of componentpart 14. Making available regeneration signal r induces control system15 to make the immediate change in the operating phase. Additionalchecking of conditions is no longer required, since the conditions incondition tester 19 had already been determined to have been satisfied.

Using the change to the second operating phase, control unit 15 is ableto initiate at least one possibly required heating measure. For example,temperature tabg of the exhaust gas may be increased, which is measuredby temperature sensor 13. The increase in temperature tabg of theexhaust gas may take place, for example, by throttling of the air flowbeing supplied to internal combustion engine 10, using the throttlevalve that is not shown. The temperature increase may also take place byan increase in recirculated exhaust gas quantity 18. As a furthermeasure, one may undertake an increase in the idling speed of internalcombustion engine 10. One other measure provides a postinjection offuel, which is combusted only incompletely in the cylinders. Theuncombusted fuel reacts exothermically in exhaust gas region 12 with anyresidual oxygen present. This measure may effectively be supported usinga secondary air injection that is not shown. Direct electrical heatingof component part 14, that is not shown, may also be provided.

The end of the second operating phase is detected using the measuresdescribed. The second operating phase is then terminated along with thechange into the first operating phase. The readiness for use ofcomponent part 14 is restored using the end of the second operatingphase, that is, the termination of regeneration.

1-11. (canceled)
 12. A method for operating a component part situated in an exhaust gas region of an internal combustion engine, comprising: in a first operating phase, embedding an exhaust gas component in the component part; in a second operating phase, regenerating the component part from the exhaust gas component; starting the second operating phase as a function of at least one of an operating state of the internal combustion engine and a loading state of the component part; and starting the second operating phase by an external start signal.
 13. The method as recited in claim 12, further comprising: conveying the external start signal via a diagnosis interface.
 14. The method as recited in claim 12, wherein the external start signal is made available by a diagnostic unit.
 15. The method as recited in claim 12, further comprising: if an external start signal is present, starting the second operating phase only if, at the same time, at least one other condition is satisfied.
 16. The method as recited in claim 15, wherein at least one of: a temperature of the internal combustion engine exceeds a prespecified threshold value, and a driving speed of a motor vehicle, in which the internal combustion engine is situated, is equal to zero.
 17. The method as recited in claim 15, wherein a rotary speed of the internal combustion engine corresponds to an idling speed.
 18. The method as recited in claim 15, wherein a performance specification signal for a performance of the internal combustion engine corresponds to a value that is sufficient only for a keeping up of an idling speed of the internal combustion engine.
 19. The method as recited in claim 15, wherein an idling controller signal made available by an idling controller is in a steady-state condition.
 20. The method as recited in claim 12, wherein the component part includes an adsorption catalyst.
 21. The method as recited in claim 12, wherein the component part includes a particulate filter.
 22. The method as recited in claim 21, wherein the particulate filter includes a Diesel particulate filter.
 23. A device for operating a component part situated in an exhaust gas region of an internal combustion engine, comprising: an arrangement for, in a first operating phase, embedding an exhaust gas component in the component part; an arrangement for, in a second operating phase, regenerating the component part from the exhaust gas component; an arrangement for starting the second operating phase as a function of at least one of an operating state of the internal combustion engine and a loading state of the component part; and an arrangement for starting the second operating phase by an external start signal. 